This part of IEC 60076 applies to the resistors used to limit the earth fault current in power systems.
Both terms Neutral Grounding Resistor (NGR) and Neutral earthing resistor (NER) can be used. However, for the purpose of this standard and in order to avoid any confusion with Neutral earthing reactor (NER), the term Neutral grounding resistor (NGR) will be used.
This standards states:
• The characteristics of the NGR
• The service conditions with which the NGR have to comply
• The tests intended for confirming that these conditions have been met and the methods to be adopted for these tests
• The information to be marked on, or given with, the NGR.
Annex A provides guidance on how to consider the effect of resistance variation with temperature.
This document applies to metallic element, dry type, natural air cooled NGR for neutral grounding of transformers and generators either directly or indirectly.
This standard applies to all NGR whether they are designed, manufactured and verified on a one-off basis or fully standardized and manufactured in quantity.
Other neutral grounding devices can be used for similar purposes as the NGR’s but are not covered by this standard.